I think perhaps not all vendor lock-in is created equal. I too shudder at the thought of walking into another Oracle like trap, but it's also an error in cognition to make the assumption that all vendors will lock you in to the same degree and in the same way.

I guess the part of us that is cautioning ourselves and others are aware of the pitfalls, but others also have valid points around going all in.

There is a matrix of different scenarios let's say.

  You can go all in on a vendor and get Oracled.
  You can go all in on an abstraction that lets you be vendor agnostic and lose some velocity while gaining flexibility.
  You can go for a vendor and perhaps it turns out that no terrible outcome results because of that. 
  You can go all in on vendor agnostic and have that be the death of the company.
  You can go all in on vendor agnostic and have that be the reason the company was able to dodge death.

Nobody can read the future and even "best practices" have a possibility of resulting in the worst outcomes. The only thing for it is to do your homework, decide what risks are acceptable to you, make your decision, take responsibility for it.